Electric meter



(No Model.)

B. THOMSON. ELECTRIC METER.

No. 532,889. Patented Jan. 22, 18915.

WITNESEEE- \/E TE] UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF SW'AMPSCOTT, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY,OF BOSTON, MASSACHUSETTS.

ELECTRIC METER.

SPECIFICATION forming part of Letters Patent No. 532,839, dated January22, 1895.

Application filed August 10, 1894. Serial 110519349. (No model.)

To whom it may concern.- The drawings show an embodiment of my Beitknown that I, ELIHU THOMs0N,a citiinvention. zen of the United States,residing at Swamp- Figure l is a longitudinal section upon the scott,inthe county of Essex, State of Massaline 1-l of Fig. 2. Fig. 2 is asection upon 5 chusetts, have invented certain new and usethe line 22 ofFig. 1. Figs. 3, 4iand 5 show fullmprovements in Electric Meters, ofwhich variations and modifications. the following is a specification. InFig. 1 M, M represent a portion of an My invention relates to electricmeters, and arc light circuit having lamps L, L, L, one or hasparticular reference to those depending or more, which may be shunted byone or 10 upon electrolytic action. It has also particumore switches, asusual. This may be a group lar application to are light circuits, wherethe of lamps lighting a store or building, a regislamps are run inseries; and has for its object try of the voltage of which is to bekept. A to produce a simple and accurate metering high resistance coilR,the resistance of which device for such circuits, upon which the poismade higher than the number of lamps 15 tential required forelectrolysis will have an around which it is placed, and alsopreferunimportant effect; that is to say, the regisably made of somematerial the resistance tration upon circuits where the potential is ofwhich increases moderately by increase in so high compared to that atwhich water detemperature, is used. In series with this are composes,that this latter potential will not two electrodes a, I), carried into avessel con- 2o affect the metering devices sufficiently to retaining asuitable electrolyte, such as dilute quire a correction. To attain theends pointed sulphuric acid. The current which traverses out, I organizemy meter as practically a mg the resistance R in shunt to the lamps L,L, istering volt meter responding mainly to the L, passes through theelectrolyte between a, variations in the voltage to be measured; 1), anddecomposes the water, giving oxygen 25 and in the case of arc lamps inseries, to and hydrogen at the poles. This causes bubwhich it isparticularly adapted, as above bles of these gases to rise from theelectrodes pointed out, I take a shunt around a number which are caughtby two compartments of of arc lamps through a resistance so high asapproximately the same shape in a vessel V, to carry but a very smallpercentage of the which is made to rock from side to side. 0 current,(one per cent. or less by preference,) This vessel is pivoted, as shownin Fig. 2, at

and in this high resistance circuit I intercathe pivots p, p and isprovided with a counlate electrodes separated by an electrolyteter-weight W, so that when it is completely which the current betweenthem decomposes, filled with fluid it is overset or overbalanced thusdischarging gases the volume of which and therefore will not be instable equilib- 35 determines the amount of current, and which brium,but will rest upon either side of its is automatically measured, ashereinafter support. The gases from the electrodes at, I) pointed out.rise and are caught in a compartment of the To the apparatus brieflyoutlined I apply vessel V, as indicated, which is open at the theprinciple of the over-set balance, or a balbottom, the gas or gasesaccumulating until 0 o ance supported below its center of gravity so thefloating power of the compartment is sufthat it will remain at rest onlywhen tipped ficient to cause the weight IV to be thrown to one side orto the other of its central posiover to the other side of the center. Atthis tion, by which means I secure a positive regmoment the gases aredischarged or allowed istering action of the meter; and I also add toescape upward through the mass of liquid 5 4 5 certain compensatingdevices, more fully in the receptacle '1'; but this movement pointed outhereinafter, adapted to increase brings the other compartment, in thiscase the accuracy of the meter by compensating the right hand one, overthe electrodes, and for variations of temperature and the barothefilling process goes on as before until gas metric pressure, which.affect the volume of is collected in sufficient amount to cause the I0050 the gas discharged, and consequently the regvessel to again tilt toits first position. This istration. goes on so long as gas is evolvedand stops when the evolution of gas stops, so that, if all the lights L,L, L, be shunted, the registry ceases. If but two of them be shuntedthere will remain three which will give a less registry in proportion,particularly as the resistance R is so high that the voltage ofdecomposition of water does not count in the process. Of course thevessel V is entirely immersed in the liquid; and its movements may byany suitable means be carried to the register D, consisting of a seriesof dials showing the number of oscillations.

The apparatus as thus constructed will be subject to certain errors,chiefly those due to variation of barometric height and to changes oftemperature. A low barometer or an increase of temperature expands thegases which are evolved and causes an accelerated movement. This howeverisin part compensated for by the fact that if R is made of metal whichincreases in resistance by increase of temperature, then the eitect isto diminish the current by such increase when the outside temperaturerises, and so compensate for the acceleration of registry due to theexpansion of the evolved gases in the vessel V. As changes due tovariations in barometric pressure could not be compensated for in thatway, in Fig. 3 I indicate a method of compensation for both variations,which consists in connecting to the vessel V a closed bulb G containinggas or air communicating with a U-shaped tube U containing a heavyliquid, like mercury. On increase in temperature the gas in G isexpanded, forcing the mercury column down in one leg and up in the otherleg of the tube U, the effect of which, if properly adjusted, is toraise the center of gravity of the vessel V and parts connectedtherewith taken as a whole. This oversets or overbalances the apparatusto a greater extent than before and it will require a larger volume ofgas in the compartments of V to cause the tipping from one side to theother, thus compensating for the expansion of the evolved gas. In thesame way a fall of the barometer would expand the gas in G and raise thecolumn of mercury, compensating for the expansion of the evolved gas dueto fall of atmospheric pressure.

In the particular arrangement illustrated in Fig. 8, the balance of thevessel V will be more or less disturbed by change of position of themercury in the tube U, in accordance with the variations of temperatureand pressure. This, however, does not effect the accuracy ofregistration, as it would only necessitate a slightly greater volume ofgas in one side or the other of the vessel to effect its tipping. Inpracticc,however, it will be found desirable to arrange the tube Usubstantially in the plane of the center of the vessel V in which theaxis of rotation is also situated, although this is not essential to thecorrect operation of the device.

In Fig. 4 the outer vessel T contains electrodes to, Z1, as before,connected in circuit with a resistance, and these electrodes are in asmall submerged bell, which, when empty of gas, sinks, and when the gashas accumulated therein to a sufficient extent, begins to rise or float.At the upper part is a stopper or valve 8, which by a float Q is heldshut until the containing vessel rises to a sufficient degree to bringthe downwardly or projecting piece a; in contact with the valve 8 atwhich moment the gas escapes by the opening of the said valve. In orderto make this action positive, it is desirable that the vessel be carriedupon an overset balance or lever, and a rod II is provided forattachment to such a lever, as shown in Fig. 5, it being so arrangedthat the center of gravity is above the point of support at 13, wherebyany tendency to rise is accentuated so that the valve 5 is positivelyopened for the discharge of the gas, and when the gas is all,or nearlyall, discharged, then and then only does the mechanism begin its return,after which the gas again collects and is again discharged, theoscillatory movements being recorded in any suitable way.

Fig. 5 also shows a further modification,in which the valve 3 rests ontop of the vessel V, which is like a bottle with the bottom out off.This valve is so held as to make a se cure joint; but upon a sufficientamount of gas accumulating from the decomposition at the electrodes a,Z), the vessel V rises in the fluid in which it is submerged until thevalve rod or lever connected with the valve 3 strikes the stop 00,opening the valve, and allowing the gas to escape; after which the valvecloses and the vessel sinks again into the fluid. Positive action isbrought about by the fact, as stated above, that the lever J is soarranged that its center of gravity is above the point of support; thatis, the whole apparatus behaves as an overset balance which can only beat rest on one side or the other of its middle position. The amount ofoversetting can be adjusted by a weight such that a given amount of gasmay be collected in V before any upward movement takes place. Thisupward movement will continue until the valve 8 is opened and the vesselV will remain in its upper position until all the gas has beendischarged from its interior, after which it will again sink.

Fig. 5 further indicates a method of partial compensation for changes inbarometric pressure. The weight Y which is used as a counterbalance forthe vessel V, may be made of solid metal and of as high specific gravityas possible, while there may be a vessel Z constructed of thin metal, asthin as practicable, which is to be exhausted of air. This vessel Zunder changes of atmospheric pressure will be more or less buoyed orfloated. When it is immersed in dense air it will be buoyed with a forceequal to the air which it displaces, and when there is a fall ofatmospheric pressure it will be buoyed with a less IIO force inaccordance with the difference of density. These actions will tend tocompensate for the expansion of the gas in V when there is a fall ofatmospheric pressure, and the condensation of such gas when there is ahigh atmospheric pressure.

Such an adjustment is made of the various compensating elementsintroduced in the apparatus as will secure a fair accuracy intheregistration.

Many changes may of course be made in the particular arrangementspointed out. For instance, where the meter is to be used on constantpotential circuits, it would be placed with its resistance in shunt to apredetermined resistance in the main circuit, and under suchcircumstances its registration would not be accurate on account of theloss in the resistance in the main circuit, which under heavy loadswould become appreciable. Such changes, or other formal ones, I aim toembrace in the claims.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In an electric meter and in combination, a vessel containing anelectrolyte, electrodes therein, a second vessel adapted to collect thegas from the electrodes and to release the same upon a definiteaccumulation, and means adapted to vary the action of the collectingvessel in accordance with variations of temperature, as herein setforth.

2. In an electric meter and in combination, a vessel containing anelectrolyte, electrodes therein, a collecting vessel arranged over suchelectrodes adapted to collect the gas released thereby and to releasethe same upon a definite accumulation thereof and means adapted to varythe action of the vessel in accordance with variations of barometricpressure, as herein set out.

3. In an electric meterandin combination, a vessel containing anelectrolyte, electrodes therein, a collecting vessel immersed in theelectrolyte arranged above the electrodes and adapted to collect the gasescaping therefrom and to release it upon a definite accumulationthereof, a support for the vessel arranged below its center of gravity,a registering train connected with the vessel adapted to register itsmovements, and means adapted to vary the times of action of the vesselto compensate for variations in temperature and atmos pheric pressure,as herein set out and described.

4. In combination, a vessel containing an electrolyte, electrodestherein, a shunt to the main circuit including such electrodes, aresistance in such shunt circuit in series with the electrodes, a vesselimmersed in the electrolyte arranged above the electrodes adapted tocollect the gas escaping therefrom and to release it upon definiteaccumulation thereof, a support for the vessel below its center ofgravity, and a registering train connected to the vessel adapted toregister its movements, as herein set out.

5. In an electric meter, a vessel containing an electrolyte, electrodestherein, a shunt circuit including such electrodes, a resistance in theshunt circuit composed of material the resistance of which is adapted toincrease by increase of temperature, a vessel immersed in theelectrolyte and adapted to collect the gas escaping from'the electrodes,such vessel having a support below its center of gravity, and aregistering apparatus operated by the movements of the vessel.

6. As a means for varying the action of an electric meter, operating byelectrolysis to accord with variations of temperature or barometricpressure, a hermetically sealed chamber and a weight adapted to opposeeach other, as herein set out; whereby variations of pressure may causea difference in the balance between the two and thus vary the times ofaction of the meter registering device, substantially as set out anddescribed herein.

In witness whereof I have hereunto set my hand this 7th day of August,1894.

ELIHU THOMSON.

Witnesses:

JOHN W. GIBBONEY, WALTER S. MOODY.

